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Renewable is Doable

Speed’s Engineers Tackle Greater Energy Efficiency

Mechanical engineering professor, Keith Sharp, and graduate student Nick Chmielewski study a new solar panel system atop Sacket Kevin Rayburn

On the roof of Sackett Hall at the Speed School, a 225-square-foot tracking solar panel follows the sun across the sky, heating water and providing electricity for the building.

At Burhans Hall on UofL’s Shelby campus, an experimental type of solar heat pipe system is being installed to heat part of the building. Nearby a photovoltaic solar system is being installed to provide part of the energy for the Biosafety Lab slated to open in 2009.

Back at Speed, a team of researchers is developing a new, low-cost solar cell with dramatically improved efficiency.

These are just a few of the practical and basic research projects under way in Speed to promote solar and other alternative energy technologies. They dovetail into new projects and will tie into UofL's new Conn Center for Renewable Energy Research and Environmental Stewardship.

As conventional energy sources become scarcer and costlier, the need to find cleaner, cheaper and more efficient alternatives grows, says Speed Dean Mickey Wilhelm.

“We have a multi-pronged effort here at Speed to involve our faculty, staff and students in renewable energy research that involves a lot of partners as we all try to improve our state and nation’s energy independence and help the Earth as well,” he says.

Some partners in the projects include the Kentucky Pollution Prevention Center (KPPC), based at Speed, as well as local, state and federal agencies, along with local schools and other community groups. Several of the projects are funded by the U.S. Department of Energy (DOE) and the Kentucky Rural Energy Consortium (KREC). U.S. Sen Mitch McConnell also has helped secure funds for many of the projects.

A better solar energy system

The experimental solar energy system being installed at a KPPC office in Burhans Hall is a DOE and KREC-supported project involving Speed mechanical engineering professors Keith Sharp and Ellen Brehob.

The system consists of a glass-covered absorber attached to copper tubes filled with SUVA-124 fluid refrigerant. As sun hits the black chrome coated absorber, heat is transferred to the tubes, heating and vaporizing the fluid. The vapor rises to the upper end of the tube, where it condenses, releasing the heat to a water tank, providing heat for the room. The system transfers heat in one direction only with virtually no loss in the reverse direction.

“Indications are that this is a more efficient system than other passive solar systems,” Sharp says.

The system promises greater efficiency especially during Kentucky’s moderately cold, moderately sunny winters, he says. The system stores excess heat for use at night as well.

Brehob says the system will be monitored for a year to see how it performs in different seasons.

Initial research indicates that the system may be twice as efficient as other solar systems in places with moderate sun and cold winters.

Mechanical engineering student Michael Albanese, as part of the team, has done computer simulations of system performance based on climates in various cities from Albuquerque, N.M., to Madison, Wis.

Solar thermal systems such as the one being studied by the Speed researchers are inherently more efficient than photovoltaic systems that convert solar heat to electricity. Their system efficiency can exceed 90 percent on warm sunny days, while current photovoltaic systems are limited to about 15 percent, Sharp says.

“The goal,” Brehob says, “is to get closer to a commercially viable system for homes and businesses.”
Meanwhile, the tracking solar panel system atop the roof of Sackett Hall integrates both photovoltaic (solar energy to electricity) and thermal (direct to heat) elements to improve energy efficiency.

Sharp says the system, which tilts toward the sun and moves with it all day as it crosses the sky, may be the first solar tracker in the state.

“The tracker gives us 30 percent more energy than stationary panels,” Sharp says. The system heats most of  the building’s water and provides enough electricity to power its computer lab.

Energy EfficiencyThe project to study the tracking system also is being done in collaboration with DOE.

Interest is especially high in the performance of the thermal solar panels because materials for those are cheaper than the intricate silicon crystals used in photovoltaic solar units. And the environmental benefits of solar systems are many.

“The solar electric part of this system is already offsetting about a thousand pounds of carbon dioxide per month. And the solar thermal system‑although we don’t yet have a readout on that—is probably offsetting even more than that,” Sharp says.

Studying the system also is mechanical engineering graduate student, Nick Chmielewski, who is gaining hands-on experience he can use in the growing sector of energy jobs.

Other energy-saving Speed research includes:

  • Computational fluid dynamics studies conducted by mechanical engineering professor, Yongsheng Lian,  to improve jet engines and reduce aircraft fuel-burn amounts by 15 percent.
  • Design and development of fuel-efficient military vehicles by a team led by mechanical engineering professor and department chair Glen Prater.
  • A major KREC-supported effort, “Photocatalysts for Solar Energy and Hydrogen Production.” The project, recently awarded $2 million by EPSCOR,   builds on ongoing work by chemical engineering faculty researchers Mahendra Sunkara, Gerold Willing and Thomas Starr to develop cheaper solar cells. The idea will be for the cells to generate electricity or produce hydrogen from water to create energy.
  • A KREC-supported project involving Eric Berson, chemical engineering assistant professor, and several University of Kentucky faculty to create ethanol from corn stover (leaves, stalk sand cobs).
  • DOE-funded studies of solar streetlights in Louisville and solar lighting in offices and class rooms, both conducted by Sharp and Barnett.

KEEPS and school initiatives

The Kentucky Energy Efficiency Program for Schools (KEEPS) program requires all schools by law to reduce their energy costs. UofL is one of three institutions helping area schools in the effort.

The KPPC has helped five school districts reduce energy use by switching to low-energy light bulbs, changing heating and air settings, replacing exit sign bulbs with LEDs, installing occupancy sensors, shutting down electronic equipment during breaks and putting timers on fans among other things.

The Kenton County School District showed the most dramatic results: $496,000 saved in two years.

Speed professor Mahendra Sunkara and Ph.D. student Praveen Meduri work on solar cell energy research.In a different project, Sharp teamed with Russ Barnett of the Kentucky Institute for Environmental and Sustainable Development (at UofL), to help engineers turn the John L. Ramsey Middle School in Louisville into a “green” facility. The U.S. Department of Energy funded the effort.

The school uses wind and solar energy to heat water and generate electricity and is built with high-tech insulation materials. Engineers plan to monitor the energy system’s performance periodically to ascertain its efficiency and success in energy and cost savings.

Energy in Transition

“We’re going to run out of fossil fuels; there’s only so much of it,” Sharp says.

“We’re in the first stages of a transition from fossil fuels toward renewables. Solar power is one of the only options we have that can supply the amount of energy we will need. It’s the most abundant resource available. The work we’re doing, hopefully, will help get us where we need to go.”

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